Propeller



.June 30 1931. w. P. VAN LAMMEREN PROPELLER Filed Nov. 20. 1930 Pafientecl June so, 1931 PATENT OFFICE wnmmvt 1. van LAMMEREN', I]?v'oonscnozvmr, 1xrnmrmnnmns PROPELLER Application filed November 20,1980, Serial No.'496907, und in Gre at Britain .Tune 18, 1929.

This invention relates t0 rotary ropellers of the type comprisingblaoles or wings pivotally mounted on axes disposed around a eommonaxisabout which the rotary pro- 5 peller carrying the blades or wings isro-.

. tatable.

The object of the present invention is to provide improvedmeans forfeathering the blades or wings during the rotati on of the propeller,for effettive driving purposeis in a s1ngle direetion.

According 150 iihe presentinventio1i, 170-- tary propellers of the typestatel are provided with one' or more symmetrically shaped lblades o1wingsand with feathering means adapted to give the blades or wings asmall negative angle of inciderice olu1ing the first part of theirupward stroke, and a small positive angle of inciolence during thesecond part ofthe said stroke, as well as 130 maintain the blades orwings, during the down stroke thereof, at right angles. o1 substantiallyat right angles to the direction in which the propeller moves, or' is tobe moved, as a whole. In order t0 carryout the said feathering movement,-it is neeessary- 130 impart a vary- -irig angular movement to eaehblaole relative -to the 1iniform movement of the rotary pro'pelle'r.Moreover, if the rotation of the propeller is in a clockwise direction,the rotatio1i o-f theblades should be in an antieloekwise .direcfiion,andl vice versa. 1 The vari'ations in the relative angula1 moveinent ofeach blade is such that only a small reve1se movementis im'parted to theblade during its up strokethe said reverse movement correspofiding to asmall decreas- 'ing negativeangle of inCidenc lurin izhe art 0f the upstroke, and a small 1n- 40 first creas1ng positive angle of incldeneedur1ng fihe second part of the saids'troke. During the down stroke ofthe blade, a eomparatively lar e reverse movement is impa rted foo theblag le' co'r1esponding to the amount of movement required in order tokeiap tl1e blade at right angles 011 sbstantially ab r1ght angles "tothe direction in which the propeller as a. whole is to be moved or ismovin As will be imderstoodfr0m the oregoing,

filed herewith, in which:

each blade rotates half a revolution oniusv own axis during eachcomplete revolution of the rotatable ropeller. Hence the necessity forthe symmetrical shape of the blade in Order to obtain the necessaryangles of incidence during each revolution.

Preferably, the feathering of the blades as above described is effee tedby gearing adapted to transmit, with a, variable velocity ratio,feathering-movement to the blades 30 or wings from driving means on therotary propeller. The said gearing may comprise toothed Wheel members ofelliptical 01 like contour, the aXes ab'out which the wheels rotatecoinciding with focal points thereof, 5

01 such non-eentral Points'of the wheels as per-mit correct. engagementof the teeth throughout the whole of the drive. A reduction g6aring mayalso be arranged be- 'tween the driven elliptical toothed wheel Fig; 3is an edge elevation of the devioe -shown in Fig. 2 and looking from therighr) in that figure;

Fig. 4 is -a section taken. substantially along the line 4-4 in Fig. 2;

Figure 5 is an enlztrged side" view of a modified gearing for featheringthe blades; Figure 6 is a fragmentar'y side viewof a modifieation of adetail of the gearing.

Throughout the drawin'gs, similar parts are indicated by the samereferen'ce' nu merals.

AS shown in Figure 1,-the rotary pro 11er fcomprises symmetric'allyshaped bla es C pivotally mounte d on radial arms 01' spokes B, one onlyof which is illustrated. The spokes B with the wings C carried therebyare rotatable as a whole about the shaft A, the direction of rotation,in the example illustrated, being anti-clockwise. In the said Figure l,a indicates the small positive angle of incidence of the blades at thetop of their rotary paths, whilst the small negative angle of incidenceof the blades is indicated by b.

The gearmg for feathering the blade C is shown best in Figs. 2, 3 and 4,from which it Will be seen that the radial arm B has a lever D sec'uredto the shaft R which is rotatably mounted in the arm B. Also secured tothe shaft R is an arm P. This arm P carries the shafts E and S, the f0rmer being rotatably mounted in the arm and the latter being preferablysecured thereto and carrying an idler L. The shaft T, rotatably mountedin another brauch 0f the arm B, is secured to the propeller blade C andcarries a gear H which meshes with the idler L. The shaft E carries thegear F which is in mesh with the idler L and elliptical gear G, Which isin mesh with a similar elliptical gear K mounted 011 the shaft R andheld against rotation relative t the arm B by means of the projections Jwhich straddle the arm B 0n opposite sides thereof as is bestillustrated in Figs. 3 and 4. The end of the arm D which is remote fromthe shaft R is piyotally connected to the rod M at N, the other endthereof being secured to the strap N fixed thereto and embraing aneccentric N, the latter being monted on a fixed support.

The operation of the feathering means is as follows:

The rotation of the arm B with its elliptical tooth'ed Wheel K about thecentral axle A imparts angular movement to the elliptical toothedWhe6lG, the ratio 0f the movement of the wheels K and G varying byvirtue of the elliptical contour thereof. -As will be clear, the wl1eelG with its shaft E makes one rev0lution for each revolution of the arm Babout tlie ax le A. This comlete revolution of the wheel G and sh aft istransmitted by-the reduction gear1ng F, L and H t0 the blade C, thereduction ratio being such that for each revolution of the shaft Ecorresponding to a complete revohition of the arm B, the blade C makesonly a half revolution, or if the arm B makes a half revolution, theblade C makes 'only a uarter revolution. As shown in F1gure 2, t earrangement of the feathering means 1s such that the blade C isfeathered as shown diagrammatically in Figure 1, the blade being kepts1ibstantially parallel to 1tself on the down stroke thereof and beingkept at a small negative angle of incidentze durmg the first part of itsup stroke and at a small positive angle of incidence during the secondpart of the up stroke. During rotatian of the arm B the arm M rotatesabout the 'eccentric N wher'eby rotary mov'ement is imparted to the armD.

The modified form of feathering gear shown in Figure 5 is distinguishedfro'm that shown in F1gures 2 and 4 inasmuch as the elliptical toothedwheel K is fixed upon the lever D instead of directly on the radial armB. Consequential upon this distinction, the other elliptical toothedwheel G and the co-axial pinion F are fulcrumed directly 011 an axle. Mon the said arm B the piriion F meshing with a pinion wheel H coaxiallymounted on the axle of the blade E as in the form of the inventiondescribed in Figures 2 to 4:.

' A further modification of the elliptical gearing hereinbeforedescribed is shown in Figure 6. As will be Seen, this modificationcomprises a pair of segmental toothed members X and Y5 which take theplace of the complete elliptical toothed wheel 0f the feathering gearingpreviously described. Virtually, the segmental toothed members X and Yconstitute a pair 0f cranks, the member X takirig the place of, andbeing mounted in similar manner t0, the lever D (Figure 5),and the twomembers X ancl Y being connected by a rod Z, the lengtli between thepivots of which is the same as the major axis of the ellipses (Figure 6)uivalent to the said segmental members If desired means may be providedfor changing the position of the axes of the elliptical toothed wheelsor equivalent members relative to thetoothed contours of the said wheelsor members, it being thereby possible to efi'ect corresponcling changein the variation of the ratio between the movement of the blades C andthe rotary prop eller as awhole.

Having now particularly described and as certainecl the nature of mysaid invention and in what manner the same is to be performed, I declarethat what I claim is:

l. In a ropeller for helicopters the combination with a blade supportrotatable about an axis, of a blade 011 said suppor't rotatable about asecond axis, an arm movable about a third axis and connected by a linkto said Support to move in predetermined relation said support when saidsupport is rotated, said link being pivoted to said arm and to saidsupport, a driving gear adapted to rotate in a predetermined directionat a speed proportional to the speed of rotation of said support andactuated by said support when the latter is moved, and a gear trainbetween said driving gear and said blade for rotating said blade at avarying speed said varying speed-of said blade being such 'that theworking surface of said blade dring the Working stroke is presented atsubstantially right angles to the direction in which the propeller as awhole moves and so that during substantially the first half of thenon-working stroke the blade is at a very slight negative angle ofincidence to the path of movement of said blade.

2. A deviee as claime d in claim 1 in whicl1 the blade occupies a smallpositive an le of' incidence to the path of movement 0 said blade during substantially all of the last half ofthe non-working stroke of saidblade.

3. In a helicopter the combination with a blade support rotatable abouta predetermined axi s, a blade rotatably mounted on said blade supportabout an axis eccentrio to said fir'st axis, a pair of armsrotatablysupported on"said blade support, one of said arms being mounted on saidbladeso as to rotate therewith, a link connecting said armseccentrically of their respective pivots, and an operating memberpivoted to said other arm and mounted to rotate about anaxis fixedwithrespect to the axis of rotation of said blade support for actuating saidarms as said blade support rotates and to thereby impart a sequence ofmovements t o said blade such that the lifting surface of the blade isat substantially right angles to the path along whi'ch the propeller asa unit is adapted to move duringthe working stroke of said blade. andthe said li fting surface coupies slight negative and positive angles ofincidence to the path 015 bodil movement of said blade duringsubstant1ally the first and last halves of the non-working stroke ofsaid. blade, respectively.

4. In a propeller the combination with an arm pivoted to rotate about asubstantially horizontal axis, of a blade carried by said arm androtatable thereon about an axis substantially parallel to said firstaxis, an.

elliptical gear secureol rigidly to said arm, a second arm pivoted tomove substantially par'allel With said first arm, an elliptit:al

gear on said seconol arm meshing with said first gear, a thirdgeardriven loy said second elliptical gearand a fourth gear meshing withsaid third gear and secured to said blade to rotate said blade when saidarms rotate, said elliptical gears Causing said blade to rotate at avariable speed such that the -lifting surfaoe of said blade issubstantially perpendicular to the line of bodily movement intended tobe given to the plane by said propeller during flight and causing' theblade to occupy a relattively small negative angle of, incidence as itbegins its non'-workinfg stroke.

5. In a propeller the combination with an arm pivoted to rotate about asubstanti'ally horizontal axis, a propeller blade support,

a blade rotatably mounted on said support about an axis substantiallyparallel to the axis of rotation of said arm, a gear for to thehelicopter by said propeller, said variable speed mechanism comprising atrain of gears the first of which is directly secured to said arm torotate therewith.

6. A device as claimed in clairn 5 in'which the propeller blade occupiesa small positive angle of incidence during the last part of itsnon-working stroke.

7. In a propeller for h elicopters, the combination with a propellerblade of a rotatable support for said propeller blade and gearing forsaid blade comprising an elliptioal gear fixeol to rotate in unison withsaid support without changing its positioh relative thereto, a secondelliptical gear meshing with said firstgear and arran d so that a linethrough its axis and said f1rst axis is maintained at substantially' thesame angle relative to the horizontal during rotation of said supportand gearing driven by said last mentioned gear forrotating saidpropeller blades one-half of a complete revolution for each revolntionof said support, said elliptical gears ca1'1sing said gears to rotateat' a speed Such that the working surface of said blade passes throi1ghsuccessive substantially parallel positions during one-half of therotation of said support said position being also such that the workingsurface of said to drive said plane and said gearing being adapted tomaintain said propeller blade With its working surface at a smallnegative angle of incidence during the first part of the reinaining halfof the revolution of said support.

8. A device as claimed in claim 7 in which the propeller blade ismaintained at a small positive angle of incidence during the last partof the movement of said support about its axis.

9. In a propellerfor helicopters the combination with a rotatablesupport adapted to rotate about a substantially horizontal axis of ablade rotatably mounted. on said support, a pair of' elliptical gearsmounted on saidsupport one of which is a driving gear and the other ofwhich is a driven gear ing said blade from said driven' gear so thatsaid blade travels through successive substantially parallel positinsduring onehalf of the rotative niovement 013 said support. and isrnaintained at substantially a slight negative angle of incidehoe to thepath of the axis cf said bla@de dnring the subsequent travel o f saidblade along its Path of movement.

'10. A devie as claimed inclaim 9 in which the blade occupies a Smallpositive angle of incidnce during the last part of the revolution cfsaid blade about th e axis .of said support.

11. In a helicopter the combination With arms mounted t0 rotate aboutdifl'erent axes and maintained in substantially parallel positionsduring rotation by a link Pivotally connected to each 0f said arms, asecond link pivoted t0 one cf saiol arms, gearteeth at the ends of saicllinks, a third link pivoted to euch of said fi rst mention6d linksadapted'to cause said sec ond link t0 rotate about its pivot as saidarms rotate ab 0ut their pivots andto cause said second link t0 rotatebodily about said first link, said gear teeth being adapted t0 causesaid first link to rotate in the prop'er direction When actuated by saidthirdlink after the first and secondlinks have been moved into alignmentwith each other, a blade rotatably mounted onthe arm to which saidsecond link is pivoted and gearing connecting said blade am]. saidseeond link so tlrat assaid second link rotates abou t its axis saidbladeWill be rb tated to impart the desired angular movements -to saldblade.

12. A device as claimed inclaim 11 in which the angular mcvement of saidblade -is such that the blade asses through substantially parallelpositions duringthe Working stroke and is maintained at small negativeand positive angles of incidence relative to the path of movement of thepropeller axi s dur ing the first an'd last portions of-the non-w0rkingstroke respectively.

In testimony that I claim the foregoing I hereunto aflix my signature.

WILLEM P. VAN LAMMEREN.

